Origin

In the sense ‘not moving’ still is Old English. The kind of still used to make whisky and other spirits is a different word, from distil (Late Middle English), which itself is based on Latin stilla ‘a drop’. The still small voice for a person's conscience, is biblical in origin. The prophet Elijah hid in a cave but was told to come out and hear the word of God. A great wind come first, then an earthquake, and finally a fire: ‘And after the earthquake a fire; but the Lord was not in the fire: and after the fire a still small voice.’ Going back at least to the 15th century is the expression still waters run deep, suggesting that a quiet or placid manner may conceal a passionate or subtle nature. A 1616 version is ‘Where rivers run most stilly, they are the deepest.’